kex: Add simple DES support for SSHv1.

include/libssh/wrapper.h

@@ -38,6 +38,11 @@ enum ssh_hmac_e {
   SSH_HMAC_MD5
 };
 
+enum ssh_des_e {
+  SSH_3DES,
+  SSH_DES
+};
+
 typedef struct ssh_mac_ctx_struct *ssh_mac_ctx;
 MD5CTX md5_init(void);
 void md5_update(MD5CTX c, const void *data, unsigned long len);
@@ -58,7 +63,7 @@ HMACCTX hmac_init(const void *key,int len, enum ssh_hmac_e type);
 void hmac_update(HMACCTX c, const void *data, unsigned long len);
 void hmac_final(HMACCTX ctx,unsigned char *hashmacbuf,unsigned int *len);
 
-int crypt_set_algorithms(ssh_session );
+int crypt_set_algorithms(ssh_session session, enum ssh_des_e des_type);
 int crypt_set_algorithms_server(ssh_session session);
 struct ssh_crypto_struct *crypto_new(void);
 void crypto_free(struct ssh_crypto_struct *crypto);

src/kex.c

@@ -56,6 +56,7 @@
 #endif
 
 #define DES "3des-cbc"
+#define SIMPLEDES "des-cbc-ssh1"
 #endif
 
 #ifdef WITH_ZLIB
@@ -93,6 +94,7 @@ const char *supported_methods[] = {
   HOSTKEYS,
   AES BLOWFISH DES,
   AES BLOWFISH DES,
+  SIMPLEDES,
   "hmac-sha1",
   "hmac-sha1",
   ZLIB,

src/kex1.c

@@ -312,6 +312,8 @@ SSH_PACKET_CALLBACK(ssh_packet_publickey1){
   ssh_string enc_session = NULL;
   uint16_t bits;
   int ko;
+  uint32_t support_3DES = 0;
+  uint32_t support_DES = 0;
   enter_function();
   (void)type;
   (void)user;
@@ -397,7 +399,10 @@ SSH_PACKET_CALLBACK(ssh_packet_publickey1){
 
   /* now, we must choose an encryption algo */
   /* hardcode 3des */
-  if (!(supported_ciphers_mask & (1 << SSH_CIPHER_3DES))) {
+  //
+  support_3DES = (supported_ciphers_mask & (1<<SSH_CIPHER_3DES));
+  support_DES  = (supported_ciphers_mask & (1<<SSH_CIPHER_DES));
+  if(!support_3DES && !support_DES){
     ssh_set_error(session, SSH_FATAL, "Remote server doesn't accept 3DES");
     goto error;
   }
@@ -406,7 +411,7 @@ SSH_PACKET_CALLBACK(ssh_packet_publickey1){
    if (buffer_add_u8(session->out_buffer, SSH_CMSG_SESSION_KEY) < 0) {
      goto error;
    }
-   if (buffer_add_u8(session->out_buffer, SSH_CIPHER_3DES) < 0) {
+   if (buffer_add_u8(session->out_buffer, support_3DES ? SSH_CIPHER_3DES : SSH_CIPHER_DES) < 0) {
      goto error;
    }
    if (buffer_add_data(session->out_buffer, session->next_crypto->server_kex.cookie, 8) < 0) {
@@ -440,8 +445,8 @@ SSH_PACKET_CALLBACK(ssh_packet_publickey1){
    }
 
    /* we can set encryption */
-   if (crypt_set_algorithms(session)) {
-     goto error;
+   if(crypt_set_algorithms(session, support_3DES ? SSH_3DES : SSH_DES)){
+      goto error;
    }
 
    session->current_crypto = session->next_crypto;

src/libcrypto.c

@@ -415,6 +415,30 @@ static void des3_1_decrypt(struct ssh_cipher_struct *cipher, void *in,
 #endif
 }
 
+static int des1_set_key(struct ssh_cipher_struct *cipher, void *key, void *IV){
+  if(!cipher->key){
+    if (alloc_key(cipher) < 0) {
+      return -1;
+    }
+    DES_set_odd_parity(key);
+    DES_set_key_unchecked(key,cipher->key);
+  }
+  cipher->IV=IV;
+  return 0;
+}
+
+static void des1_1_encrypt(struct ssh_cipher_struct *cipher, void *in, void *out,
+                           unsigned long len){
+
+  DES_ncbc_encrypt(in, out, len, cipher->key, cipher->IV, 1);
+}
+
+static void des1_1_decrypt(struct ssh_cipher_struct *cipher, void *in, void *out,
+                           unsigned long len){
+
+  DES_ncbc_encrypt(in,out,len, cipher->key, cipher->IV, 0);
+}
+
 #endif /* HAS_DES */
 
 /*
@@ -539,6 +563,18 @@ static struct ssh_cipher_struct ssh_ciphertab[] = {
     des3_1_encrypt,
     des3_1_decrypt
   },
+  {
+    "des-cbc-ssh1",
+    8,
+    sizeof(DES_key_schedule),
+    NULL,
+    NULL,
+    64,
+    des1_set_key,
+    des1_set_key,
+    des1_1_encrypt,
+    des1_1_decrypt
+  },
 #endif /* HAS_DES */
   {
     NULL,

src/libgcrypt.c

@@ -262,6 +262,17 @@ static void aes_decrypt(struct ssh_cipher_struct *cipher, void *in, void *out,
   gcry_cipher_decrypt(cipher->key[0], out, len, in, len);
 }
 
+static int des1_set_key(struct ssh_cipher_struct *cipher, void *key){
+  if(!cipher->key){
+    if (alloc_key(cipher) < 0) {
+      return -1;
+    }
+    DES_set_odd_parity(key);
+    DES_set_key_unchecked(key,cipher->key);
+  }
+  return 0;
+}
+
 static int des3_set_key(struct ssh_cipher_struct *cipher, void *key, void *IV) {
   if (cipher->key == NULL) {
     if (alloc_key(cipher) < 0) {
@@ -285,6 +296,19 @@ static int des3_set_key(struct ssh_cipher_struct *cipher, void *key, void *IV) {
   return 0;
 }
 
+
+static void des1_1_encrypt(struct ssh_cipher_struct *cipher, void *in, void *out,
+                           unsigned long len, void *IV){
+
+  DES_ncbc_encrypt(in, out, len, cipher->key, IV, 1);
+}
+
+static void des1_1_decrypt(struct ssh_cipher_struct *cipher, void *in, void *out,
+                           unsigned long len, void *IV){
+
+  DES_ncbc_encrypt(in,out,len, cipher->key, IV, 0);
+}
+
 static void des3_encrypt(struct ssh_cipher_struct *cipher, void *in,
     void *out, unsigned long len) {
   gcry_cipher_encrypt(cipher->key[0], out, len, in, len);
@@ -461,6 +485,17 @@ static struct ssh_cipher_struct ssh_ciphertab[] = {
     .cbc_encrypt     = des3_1_encrypt,
     .cbc_decrypt     = des3_1_decrypt
   },
+  {
+    .name            = "des-cbc-ssh1",
+    .blocksize       = 8,
+    .keylen          = sizeof(DES_key_schedule),
+    .key             = NULL,
+    .keysize         = 64,
+    .set_encrypt_key = des1_set_key,
+    .set_decrypt_key = des1_set_key,
+    .cbc_encrypt     = des1_1_encrypt,
+    .cbc_decrypt     = des1_1_decrypt
+  },
   {
     .name            = NULL,
     .blocksize       = 0,

src/packet_cb.c

@@ -143,7 +143,7 @@ SSH_PACKET_CALLBACK(ssh_packet_newkeys){
      * Set the cryptographic functions for the next crypto
      * (it is needed for generate_session_keys for key lengths)
      */
-    if (crypt_set_algorithms(session)) {
+    if (crypt_set_algorithms(session, SSH_3DES) /* knows nothing about DES*/ ) {
       goto error;
     }
 

src/wrapper.c

@@ -228,18 +228,18 @@ error:
   return rc;
 }
 
-static int crypt_set_algorithms1(ssh_session session) {
+static int crypt_set_algorithms1(ssh_session session, enum ssh_des_e des_type) {
   int i = 0;
   struct ssh_cipher_struct *ssh_ciphertab=ssh_get_ciphertab();
 
   /* right now, we force 3des-cbc to be taken */
   while (ssh_ciphertab[i].name && strcmp(ssh_ciphertab[i].name,
-        "3des-cbc-ssh1")) {
+        des_type == SSH_DES ? "des-cbc-ssh1" : "3des-cbc-ssh1")) {
     i++;
   }
 
   if (ssh_ciphertab[i].name == NULL) {
-    ssh_set_error(session, SSH_FATAL, "cipher 3des-cbc-ssh1 not found!");
+    ssh_set_error(session, SSH_FATAL, "cipher 3des-cbc-ssh1 or des-cbc-ssh1 not found!");
     return SSH_ERROR;
   }
 
@@ -258,8 +258,8 @@ static int crypt_set_algorithms1(ssh_session session) {
   return SSH_OK;
 }
 
-int crypt_set_algorithms(ssh_session session) {
-  return (session->version == 1) ? crypt_set_algorithms1(session) :
+int crypt_set_algorithms(ssh_session session, enum ssh_des_e des_type) {
+  return (session->version == 1) ? crypt_set_algorithms1(session, des_type) :
     crypt_set_algorithms2(session);
 }